program four;

{$APPTYPE CONSOLE}

uses
  SysUtils;

var
  n, k, i, t, v, x: integer;

begin
  readln(n);
  readln(k);
  t:=1;
  v:=1;
  x:=1;
  if (n>=k) then
  begin
    for i:=1 to n do
      t:=t*i;
    for i:=1 to k do
      v:=v*i;
    for i:=1 to n-k do
      x:=x*i;
    writeln(t div(v*x));
  end
  else
    writeln('0');
  readln;
end.
